skeletal system powerpoint lecture

Skeletal System

Functions•Support•Protection•Muscle Attachment•Production of blood cells and platelets•Storage

Bone Tissue• All bones are composed of two

types of osseous tissue:

• Compact bone is the thick, hollow part of the bone.▫ Found in greater amounts in

supportive and protective bones.• Spongy bone is found at the

ends of the bones. This is made of smaller pieces of bone with lots of empty spaces that will hold red bone marrow.▫ Red Bone Marrow is responsible

for the production of blood cells.▫ In adolescence, RBM disappears

from all bones except the ribs, sternum, vertebrae, and the proximal ends of the femur and humerus.

Classification of Bones

•Long bones are longer than they are wide, with heads at each end.▫Mostly made of

compact bone.▫Examples include the

femur and humerus.


•Short bones are often cube-shaped, and contain higher amounts of spongy bone.▫Examples include

the bones of the wrist (carpals) and ankle (tarsals).


•Flat bones are thinner, flattened, and often curved.▫Made of thin

layers of compact and spongy bone.

▫Examples include the skull, ribs, and sternum.


•Irregular bones do not fit into any of the other categories due to their unusual shapes.▫Examples

include the vertebrae and pelvic bones.

Anatomy of a Long Bone

•Long bones are divided into three sections:▫Proximal epiphysis is

the end of the bone closest (“approximate”) to the trunk of the body.

▫Diaphysis is the middle shaft of the bone.

▫Distal epiphysis is the end of the bone farthest (“distant”) to the trunk of the body.


•The diaphysis is covered by a layer of dense fibrous tissue called the periosteum.

•The medullary cavity is the hollowed out area inside the shaft.▫Contains yellow marrow

(fat storage) in adults.▫Red marrow (blood cell

formation) in infants.


Proximal Epiphysis

Diaphysis

Distal Epiphysis

Spongy Bone

Compact Bone

Medullary Cavity

Periosteum

Microscopic Anatomy of Bone•Bone tissue is characterized by ring-

shaped lamellae. •Each layer of a lamella contain pits called

a lacunae, which contains the bone cells.

Microscopic Anatomy of Bone•Haversian canals

at the center of each osteon contains theblood vessels to nourish the bone.

•Volkmann’s canals join the Haversian canals together.

Microscopic Anatomy of Bone

•There are two types of bone cells.▫Osteoblasts lay down the

minerals needed to build the bone.

▫Osteoclasts shape the bone into the appropriate form.

•The cells are all connected back to the nutrient supply through tiny canals called canaliculi.

Microscopic Bone Anatomy

Haversian Canal

Lamella

Lamella

Osteocyte

Canaliculus

Lacuna

Lacuna

Bone Growth

•Bones continuously grow and lengthen throughout childhood.

•Bones of embryos are mostly hyaline cartilage.▫This cartilage is gradually replaced by bone

in a process called ossification.•Growth plates are layers of cartilage

that are replaced by bone and regrow until adulthood. They are also called epiphyseal plates.

Long Bone Formation and Growth

Bone startingto replacecartilage

In an embryo

Bone collar

Hyalinecartilagemodel

(a)



In a fetusIn an embryo

Growthin bonelength

Bloodvessels

Hyalinecartilage

New center ofbone growth

Medullarycavity

Bone collar


(a)



Epiphysealplatecartilage

Articularcartilage

Spongybone

In a childIn a fetusIn an embryo

New boneforming

Growthin bonewidth

Growthin bonelength

Epiphysealplate cartilage

New boneforming

Bloodvessels

Hyalinecartilage

New center ofbone growth

Medullarycavity

Bone collar


(a)

Bone Formation

The Skeleton

•The skeleton is divided into two regions:•The axial skeleton includes everything

around the longitudinal (vertical) center plane of the body.▫Skull, spine▫80 bones

•The appendicular skeleton includes the appendages: the arms and legs.

•Bones of arms and legs•126 bones

The Skull

•Most of the bones of the skull are flat, designed to be protective.

•Each bone is joined by a suture, a joint made of dense fibrous tissue.

Fontanels•The fetal skull has a

few sutures that are much wider, called fontanels.▫These allow the brain

to grow and expand.▫Convert to bone

within about 2 years.•Fontanels are the soft

spots on the heads of infants.

Skull, lateral view

Frontal Bone

Nasal Bone

Zygomatic Bone

Maxilla

Mandible

Temporal Bone

Occipital Bone

Sphenoid Bone

Parietal Bone

Sinuses•Sinuses are

hollow bones with thin plates between them designed to drain fluids.▫Sinus headaches

happen when they get blocked and the fluids overflow into the nasal cavity.

The Hyoid Bone

•The only bone in the entire body that does not form a joint with any other bone.

•The base of the tongue attaches to this bone, and it aids in swallowing and speech.

Ear

•The middle ear is made up of three small bones.▫Malleus (hammer)▫Incus (anvil)▫Stapes (stirrup)

Vertebral Column•There are 24 vertebral bones, each separated by

a disk of fibrocartilage.•The vertebrae are named based on their location.

▫C1-C7 – Cervical vertebrae in the neck C1 is called the atlas C2 is called the axis

▫T1-T12 – Thoracic vertebrae in upper back.▫L1-L5 – Lumbar vertebrae in the lower back.

•Two bones found below the lumbar region, made from nine vertebrae fused together.▫Sacrum▫Coccyx

Vertebral Column

CervicalC1-C7

LumbarL1-L5

Thoracic

T1-T12

Sacrum

Coccyx

AtlasAxis

Ribs and Sternum

•Protect major organs of the thoracic cavity.▫Heart▫Lungs

•There are three sets of ribs:▫True ribs (pairs 1-7) are connected

directly to the sternum.▫False ribs (pairs 8-12) are connected to

the sternum through cartilage or not at all. Floating ribs (pairs 11 and 12) are false ribs

only connected to the thoracic vertebrae.

Sternum and Ribs

Manubrium

Sternum

Xiphoid Process

True Ribs: 1-7

False Ribs: 8-10

Floating Ribs: 11-12

The Appendicular SkeletonFrontal Bone

Sacrum

Ulna

Carpals

Metacarpals

Phalanges

Radius

Rib Cage

Sternum

Mandible

Maxilla

Coccyx

Occipital Bone

Scapula

Clavicle

Parietal Bone

Humerus

Vertebral Column

The Appendicular Skeleton

Fibula

Tarsals

Phalanges

Tibia

Talus

Pelvis

Femur

Patella

Metatarsals

Joints•Locations where

bones join together are called joints.

•Ball and socket joints are found in the shoulder and hip. ▫Have the greatest

range of motion (360˚)

Angular Joints•Angular joints

are found in the wrist and ankle. These allow movements in many angles, but not as free as ball and socket.

Hinge Joints•Hinge joints

perform a simple open-and-close motion.▫Elbow, knees,

phalanges.

Pivot Joints•Pivot joints are only

found between the axis and atlas vertebrae.▫Allow the head to

turn side-to-side.

Gliding Joints•Gliding joints are

able to slide back and forth on each other, creating sideways movement.▫Found in the carpals

and tarsals.

Slightly Moveable Joints•Slightly moveable

joints can only expand slightly.▫Symphysis pubis

between the pelvic bones can expand to accommodate childbirth.

Immoveable Joints•Immoveable joints

cannot move at all. ▫Sutures between the

bones of the skull.

Connective Tissue

•Tendons attach muscle to bone.

•Ligaments attach bone to bone.

Connective Tissue

•Articular cartilage is found at the ends of bones.▫Cushions bone-on-bone contact.▫Breaks down over time (arthritis).

Bursa

•Bursa are little fluid filled sacs in some joints (knee and elbow) that cushion the joint. ▫ Synovial Fluid is found in between the bursa.

Injuries

Sprains

•Sprains are a stretching/tearing of the ligament tissue.▫Occur when a joint

is forced into an abnormal position

Dislocations

•Disruption of integrity of a joint

•When a bone is pulled out of the socket.

Simple Fractures

• When the bone fractures completely but does not puncture the skin.

Compound

•When the bone breaks and comes through the skin.

Greenstick Fractures

• When the fracture does not go through the entire bone, or when it splinters.

• Happens in children with cartilage also.

• Like pulling a branch off a living tree.

skeletal system powerpoint lecture

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